Overflow arrangement

ABSTRACT

An aerobic sewage treatment system includes a plurality of series-connected aerated digestion chambers. In order to prevent passage of solids from one chamber to the next downstream chamber the liquid connection between the chambers is formed by a specially shaped conduit having an open inlet end disposed within a quiet portion of its respective chamber.

Unite States Patent 11 1 Hargraves 1 July 31, 1973 [5 1 OVERFLOW ARRANGEMENT 2,852,140 9/1958 MacLaren.... 210 221 1 1 Inventor: William aw- 133 Lake #2331333 3/1338 'vv21;1;;;11':::.. ....:'513/54? Highlander, Dunedin, Fla. 33528 22 d; Apt 19 1971 Primary ExaminerSamil1 N. Zaharna Assistant Examiner-F. F. Calvetti [2]] APP! 135,353 Attorney-Cushman, Darby and Cushman [52] US. Cl 210/199, 210/201, 210/207, ABSTRACT 210/221, 210/322 An aerobic sewage treatment system includes a plural- [51] Int. Cl B0111 21/08 ity of series-connected aerated digestion chambers. In [58] Field of Search 210/63, 199, 201 order to prevent passage of solids from one chamber to 210/205, 221, 322, 84, 207 the next downstream chamber the liquid connection between the chambers is formed by a specially shaped [56] References Cited conduit having an open inlet end disposed within a UNITED STATES PATENTS quiet portion of its respective chamber. 2,486,691 11/1949 Travers 210/201 X 6 Claims, 3 Drawing Figures /8 /6 A. 22 /0 24-4- j l l fa/F d. E 43 1' 4 4 i\ .50 Z1 2; 26 Z ZZZ-1: II-'1- :1C. 11' Z 2. -20 -10 OVERFLOW ARRANGEMENT This invention relates to multistage aerobic sewage treatment systems and in particular to the construction of the liquid connections between the digestion stages and to the internal configuration of the stages.

FIG. 1 is a schematic vertical sectional view of a multistage aerobic system embodying the principles of the present invention;

FIG. 2 is a sectional view taken on the line 2-2 of FIG. 1; and

FIG. 3 is a partial sectional view of a modified digestion chamber.

FIGS. 1 and 2 illustrate in simplified form a multistage aerobic digestion system having a main digestion chamber and a plurality of secondary digestion chambers 12, l4, l6 and 18 separated from each other by partitions 20. The main chamber 10 is provided with an inlet 22 for receiving undigested raw sewage. A more detailed description of this type of system appears in my application Ser. No. 813,242, filed Apr. 3, 1969, now abandoned.

Each chamber is divided into a mixing and aerating portion 24 and a quiet portion 26 by a suitable baffle arrangement. in the illustrated embodiment each chamber includes two downwardly facing concave baffles 28 and 30 disposed generally on opposite sides of the chamber. These baffles also cooperate with an upwardly facing concave bottom wall 32 and with an aerator device 34 to mix the contents of the chamber as shown by the arrows in FIG. 2. The aerator device 34 may be a horizontal perforated tube or one or more conventional air stones located at or near the lowermost point in the chamber and next to the respective side wall 36.

in accordance with the principles of the present invention the liquid connection between digestion chambers is made in'such' a manner that there will be little or no tendency for solid material to flow from one chamber to another, the purpose of this featurebeing to prevent entry of raw sewage into the downstream stages. At the same time it is desirable to avoid the use of filters for this purpose because in the event of a closgged filter the upstream stages will overflow during operation. The present invention accomplishes this objective by providing unobstructed, specially-shaped conduit connections 37 between a quiet portion of an upstream stage and an aerating portion of the adjacent downstream stage. The configuration of the quiet portion is not critical, and the quiet portions 26 defined between the baffles 28 and the adjacent side walls 38 is merely illustrative. However, the structure which defines a quiet portion should extend above liquid level 40 to prevent floating solids from approaching the connection 37. Also, the structure should include 'a bottom opening,'such as shown at 42, in communication with the aerating portion 24 to allow any solids finding their way into the portion 26 to settle and return to the portion 24.

Each ofthe connections 37 is constructed as a double elbow having a horizontal inlet portion 44' disposed below liquid level 40, a vertical portion 46 extending to above liquid level 40, and a horizontal outlet portion 48 projecting through the respective portion 20. Preferably, the inlet aperture faces the partition and is closely spaced therefrom. Also, it is preferred to provide a baffle 50 below the inlet aperture to prevent any rising solids from approaching the inlet aperture. The illustrated baffle 50 is a flat plate secured to the partition 20 and extending downwardly and in an upstream direction as viewed in FIG. 1 The size of the quiet portion 26 should be larger in volume than the greatest maximum expected intake volume of the main chamber 10 at any one time or hour.

in operation organic waste is delivered to the main chamber through the inlet 22, causing an increase in liquid level with the result that liquid flows sequentially through the chambers via the connectors 37. The liquid is thoroughly agitated and aerated in each chamber portion 24, but the agitated solids do not pass into the portions 26. Therefore, raw sewage particles are retained in the main chamber 10, and the liquid in each successive chamber l2, l4, l6 and 18 is progressively purified by aerobic digestion.

FIG. 3 illustrates a modification in which the quiet chamber portion 26' is defined between a partition 20' and a vertical transverse baffle 52 which extends between the side walls of the chamber.

What is claimed is:

1 A digestion treatment system for purifying organic waste material dissolved in or dispersed in water comprising: walls defining a main digestion chamber having inlet means for receiving organic waste material and walls defining a plurality of separate secondary digestion chambers, each of said secondary chambers including baffle means dividing the chamber into an agitating and aerating portion and a smaller quiet portion which are in communication with each other only through a submerged passageway of relatively small cross-sectional area; means in each agitating and aerating portion for introducing air bubbles into the liquid in that portion and for mixing the entire liquid contents of that portion; and conduit means for connecting the quiet portion of each secondary chamber to the aerating portion of one other chamber to thereby provide for flow of liquid waste from the main chamber sequentially through the secondary chambers to an outlet means, each conduit means having an unobstructed bore and including a horizontally facing inlet aperture disposed below the liquid level in the quiet portion of the respective secondary chamber, a vertical tubular portion extending upwardly through the liquid surface, and a-horizontally facing outlet aperture disposed at the liquid level in the aerating portion of the downstream chamber.

2. Apparatus as in claim 1 wherein each said baffle means which divides a secondary chamber into an acrating portion and a quiet portion includes a downwardly concave baffle having an upper end disposed at about liquid level and a lower end disposed below the respective conduit means andwherein the respective aerating and mixing means includes means for introducing air bubbles into the bottom of the aerating 'portion at a location remote from the respective conduit means and an additional concave baffle which directs the rising air bubbles toward said first-named baffle as turc.

6. Apparatus as in claim 5 wherein each chamber is separated from the adjacent downstream chamber by a common vertical wall, said conduit means being located at the common wall, and said bafflc extending from the common wall. 

1. A digestion treatment system for purifying organic waste material dissolved in or dispersed in water comprising: walls defining a main digestion chamber having inlet means for receiving organic waste material and walls defining a plurality of separate secondary digestion chambers, each of said secondary chambers including baffle means dividing the chamber into an agitating and aerating portion and a smaller quiet portion which are in communication with each other only through a submerged passageway of relatively small cross-sectional area; means in each agitating and aerating portion for introducing air bubbles into the liquid in that portion and for mixing the entire liquid contents of that portion; and conduit means for connecting the quiet portion of each secondary chamber to the aerating portion of one other chamber to thereby provide for flow of liquid waste from the main chamber sequentially through the secondary chambers to an outlet means, each conduit means having an unobstructed bore and including a horizontally facing inlet aperture disposed below the liquid level in the quiet portion of the respective secondary chamber, a vertical tubular portion extending upwardly through the liquid surface, and a horizontally facing outlet aperture disposed at the liquid level in the aerating portion of the downstream chamber.
 2. Apparatus as in claim 1 wherein each said baffle means which divides a secondary chamber into an aerating portion and a quiet portion includes a downwardly concave baffle having an upper end disposed at about liquid level and a lower end disposed below the respective conduit means and wherein the respective aerating and mixing means includes means for introducing air bubbles into the bottom of the aerating portion at a location remote from the respective conduit means and an additional concave baffle which directs the rising air bubbles toward said first-named baffle as the bubbles approach roach the surface of the liquid.
 3. Apparatus as in claim 2 wherein the quiet portion of each secondary chamber is defined between an upright wall of that chamber and said first-named baffle and wherein the passageway between the chamber portions is defined by a space betwen said upright wall and the lower end of said first-named baffle.
 4. Apparatus as in claim 1 wherein each said conduit means is formed as a double elbow with the inlet and outlet apertures facing downstream.
 5. Apparatus as in claim 4 including an inclined baffle disposed below the inlet aperture of each conduit means and extending downwardly from a point downstream of the aperture to a point upstream of the aperture.
 6. Apparatus as in claim 5 wherein each chamber is separated from the adjacent downstream chamber by a common vertical wall, said conduit means being located at the common wall, and said baffle extending from the common wall. 